It's Time For a Hard Bitcoin Fork

It's in Bitcoin community's, and GHash's, economic interest that no miner exceeds 50%. That's all you need to know to know that this is just another exasperated hand-wringer proclaiming the premature death of BitCoin.

BitCoin, RIP 2008 - 2009, 2010, 2011, 2012, 2013, 2014, ?

Are Bitcoin community's interests and individual miners' interests aligned? I understand why the bitcoin community wouldn't want a mining pool with more than 50% of the share, but why should "selfish" individual miners care?

It's certainly true that selfish mining strategy A which gave a 5% increase in results would lose out to another selfish mining strategy B which gave 10% increases in results. However that's not an argument that strategy A doesn't break the system, merely that the optimal selfish strategy breaks the system at least badly as strategy A.

Now it is possible that there isn't a stable strategy to use. If we supposed for the purposes of argument that the fair weather strategy was more profitable than the selfish strategy described in the first article you posted, then it would seem that the optimal strategy would oscillate. As more people participate in a selfish pool consistently the more profitable it is to be a fair weather miner. However, supposing that leads to a dissolution of the selfish pool all those fair weather miners turn honest. Against honest miners, however, the selfish strategy is proven to be more profitable. And so you'd see an oscillation where people constantly shift between being honest, selfish and fair weather.

Of course, if the long run gains keeping up on this strategy treadmill is less than simply sticking to the selfish strategy through thick and thin, then perhaps the fair weather strategy isn't better in reality.

He took a gamble: that the bold tweeted prediction would increase attention for his paper (which it did), and then come true, improving his credibility about such matters (which it didn't).

He's now saying "I told you so", literally, in a gambit for more credibility – but eliding mention of his prior bad predictions. (In addition to the "good time to sell" prediction, I would point out that (a) orphan rates since his paper was published have not shown the predicted wide self-interested adoption of "selfish mining"; (b) the pool that's achieved 51% does not appear to have used "selfish mining" to get there - just the same economies-of-scale and small-miner-superstitions that have been known threats since the beginning of pooled-mining. In other words, even if this is a disaster, it's not the same one, by the same path, as he predicted – but an older potential doom, prophesied by others long before his work.)

When facing such a claim of earned authority, it's entirely appropriate, and not at all ad hominem, to highlight the full record. To "shout from the rooftops" exactly the same early calls he himself would be bragging about – if he'd been right.

There's pretty much an infinite number of reasons people choose short-term profit with apparent long-term opportunity cost above what apparently stable long-term profit streams. Betting that an actor with the power to do so would never do so usually is equivalent to creating a greater incentive for them to do so.